EP4241076A2 - Système de détection thermodynamique découplé - Google Patents

Système de détection thermodynamique découplé

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Publication number
EP4241076A2
EP4241076A2 EP21899299.8A EP21899299A EP4241076A2 EP 4241076 A2 EP4241076 A2 EP 4241076A2 EP 21899299 A EP21899299 A EP 21899299A EP 4241076 A2 EP4241076 A2 EP 4241076A2
Authority
EP
European Patent Office
Prior art keywords
sensor
oxide
catalyst
thin
detection device
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
EP21899299.8A
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German (de)
English (en)
Inventor
Peter P. RICCI
Otto J. Gregory
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Trace Sensing Technologies Inc
Original Assignee
Trace Sensing Technologies Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Trace Sensing Technologies Inc filed Critical Trace Sensing Technologies Inc
Publication of EP4241076A2 publication Critical patent/EP4241076A2/fr
Pending legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
    • G01N33/0004—Gaseous mixtures, e.g. polluted air
    • G01N33/0009—General constructional details of gas analysers, e.g. portable test equipment
    • G01N33/0011—Sample conditioning
    • G01N33/0013—Sample conditioning by a chemical reaction
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
    • G01K17/00—Measuring quantity of heat
    • G01K17/06—Measuring quantity of heat conveyed by flowing media, e.g. in heating systems e.g. the quantity of heat in a transporting medium, delivered to or consumed in an expenditure device
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/02—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance
    • G01N27/04—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance
    • G01N27/12—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance of a solid body in dependence upon absorption of a fluid; of a solid body in dependence upon reaction with a fluid, for detecting components in the fluid
    • G01N27/122—Circuits particularly adapted therefor, e.g. linearising circuits
    • G01N27/123—Circuits particularly adapted therefor, e.g. linearising circuits for controlling the temperature
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/02—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance
    • G01N27/04—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance
    • G01N27/12—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance of a solid body in dependence upon absorption of a fluid; of a solid body in dependence upon reaction with a fluid, for detecting components in the fluid
    • G01N27/128—Microapparatus
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
    • G01N33/48—Biological material, e.g. blood, urine; Haemocytometers
    • G01N33/483—Physical analysis of biological material
    • G01N33/497—Physical analysis of biological material of gaseous biological material, e.g. breath
    • G01N33/4975—Physical analysis of biological material of gaseous biological material, e.g. breath other than oxygen, carbon dioxide or alcohol, e.g. organic vapours
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N25/00—Investigating or analyzing materials by the use of thermal means
    • G01N25/18—Investigating or analyzing materials by the use of thermal means by investigating thermal conductivity
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
    • G01N33/0004—Gaseous mixtures, e.g. polluted air
    • G01N33/0009—General constructional details of gas analysers, e.g. portable test equipment
    • G01N33/0027—General constructional details of gas analysers, e.g. portable test equipment concerning the detector
    • G01N33/0036—General constructional details of gas analysers, e.g. portable test equipment concerning the detector specially adapted to detect a particular component
    • G01N33/0057—Warfare agents or explosives

Definitions

  • thermodynamic sensing platform for the detection of chemical compounds in the vapor phase at the single molecule level.
  • This thermodynamic sensor platform may be referred to herein as a “decoupled thermodynamic sensor.”
  • the sensing system described within decouples the heating and sensing functions, resulting in unparalleled sensor selectivity and sensitivity at the single molecule level.
  • the decoupled thermodynamic sensor described within has been used to detect chemical compounds, including explosives (including triacetone triperoxide (TATP) and dintrotoluene (DNT)), narcotics and drugs (including fentanyl and cocaine), hallucinogenic and non- hallucinogenic compounds (including cannabidiol (CBD) and tetrahydrocannabinol (THC)), and a variety of other VOCs (acetone, natural gas, propane, etc.).
  • the sensing system is especially designed for a variety of healthcare applications including breathalyzers and wearables.
  • the decoupled thermodynamic sensing system has been used to detect breath, skin, and sweat biomarkers related to variety of chronic and acute diseases (including diabetes, chronic kidney disease (CKD), Alzheimer’s, and cancer).
  • Sensors utilizing microheaters have been shown to be effective in detecting explosives such as triacetone triperoxide (TATP) in the vapor phase at trace levels.
  • TATP triacetone triperoxide
  • Such sensors include those described in U.S. Patent No. 9,759,699 to Gregory et al. and Ricci et ah, "Continuous Monitoring of TATP Using Ultrasensitive, Low-Power Sensors," published on 09 July 2020 in IEEE Sensors Journal, the entire contents of each of which are incorporated herein by reference. While those sensors are extremely effective, it is desirable to provide sensors having increased sensitivity.
  • Those existing chemical sensors comprise relatively thick (measured in hundreds of micrometers) alumina substrates, relatively thick nickel films for the microheaters, and a thick passivation layer between the heater and the catalyst. Additionally, a temperature of approximately 500 °C is required to operate these sensors, and therefore a significant amount of power is required for the heaters. The relatively large thermal mass of the components of these sensors further adds to the required power to operate. Additionally, these sensors contained a substrate that was isotropic, which transferred heat in all directions. This large thermal mass in combination with the lateral heat transfer was found to affect the accuracy of the heat measurements of the catalyst.
  • thermodynamic sensing system with unparalleled sensitivity.
  • a thermodynamic sensing system is “decoupled” if a heating device of the system is separate from and not in contact with a thin-film sensor in the system.
  • An example of a decoupled detection device includes one in which a substrate is disposed between a microheater and a thin-film sensor.
  • Embodiments of a decoupled sensor can operate at temperatures much lower than 175°C and use considerably less power than known sensors.
  • embodiments of a thermodynamic sensing system in accordance with the present invention have decoupled heating and sensing layers resulting in improved sensitivity and are capable of single molecule detection, i.e. detecting a single molecule of a chemical compounds in the vapor phase.
  • the senor comprises a copper-based microheater deposited onto ultrathin ( ⁇ 40pm thick) yttria-stabilized-zirconia substrates, which results in improved heating efficiency due to the electrical and thermal conductivity of the copper.
  • the sensor comprises a palladium-based microheater deposited onto the opposite face of the ultrathin yttria-stabilized-zirconia substrates, which results in increased sensor sensitivity and selectivity over known devices.
  • Embodiments of a decoupled thermodynamic sensor display highly anisotropic thermal characteristics, which results in localized heating between substrate surfaces.
  • Embodiments of a decoupled thermodynamic sensor require that the microheaters be precisely aligned as such to guarantee optimal heating efficiency with corresponding improvements to the power efficiency.
  • Embodiments of a decoupled thermodynamic sensor have displayed the ability to detect one or more chemical compounds in the vapor phase at the single molecule level with relatively minimal power requirements.
  • a detection device includes at least one multi-layer sensor.
  • the sensor(s) has four layers.
  • the sensor may include a first layer having a microheater (e.g., a metallic microheater) configured to receive power at a first power level to reach a setpoint temperature, a second layer in contact with the first layer, a third layer in contact with the second layer, and a fourth layer in contact with the third layer.
  • the second layer may be a substrate.
  • the third layer may be a thin-film metallic sensor configured to measure the power level resulting from heat effects due to chemical reactions.
  • the fourth layer may include a catalyst configured to undergo a chemical reaction when exposed to an analyte.
  • the chemical reaction may be endothermic or exothermic.
  • the metallic microheater may receive power at a first power level to maintain a setpoint temperature and provide heat to the metallic sensor.
  • the metallic sensor may receive power at a second power level to measure the response after the catalyst begins the chemical reaction.
  • the metallic microheater may be copper.
  • the substrate may be yttria-stabilized-zirconia.
  • the thin-film sensor may be palladium.
  • the catalyst may be a metal oxide catalyst.
  • the substrate may have a thickness of less than 40 micrometers.
  • the detection device may detect the analyte in a vapor phase based on the heat effect.
  • the detection device may detect the analyte at concentration levels as low as a single molecule level.
  • the detection device may include a controller configured to cause the power to be provided to the metallic microheater at the first power level to reach the setpoint temperature, to cause the power to be provided to the metallic sensor at the second power level to maintain the setpoint temperature after the catalyst begins the chemical reaction, and determine an existence, identity, and/or concentration of the analyte based on monitoring the second power level.
  • the detection device may determine the existence, identity, and/or concentration of one or more additional analytes as well.
  • the detection device may include a reference sensor that is not coated with a catalyst.
  • the detection device may include a second decoupled sensor having a second microheater and a second thin-film sensor in thermal communication with a second catalyst different from the first catalyst.
  • the detection device may include third, fourth, and fifth sensors comprising third, fourth, and fifth catalysts, respectively.
  • the first catalyst comprises aluminum copper oxide (AhCuC )
  • the second catalyst comprises iron oxide (Fe 2 0 3 )
  • the third catalyst comprises indium-tin oxide (ITO)
  • the fourth catalyst comprises tin oxide (SnO)
  • the fifth catalyst comprises tungsten oxide (WO).
  • the detection device may include a sixth sensor comprising a sixth catalyst selected from copper oxide (CuO) or manganese oxide (MnO).
  • a detection device is provided with an array of sensors that are electrically coupled to a controller.
  • Each sensor in the array may have its own distinct catalyst such that reactions between an analyte(s) and the distinct catalysts (to the extent a reaction occurs) indicate information on the existence, identity, and/or concentration of the analyte(s).
  • the reactions may be thermal, and the controller may monitor the variations in power applied to each sensor to determine the existence, identity, and/or concentration of the analyte(s).
  • Each of the sensors in the array may be formed from the multi layer configuration described above with its own distinct catalyst.
  • a reference sensor may be included in the array that is formed in the multi-layer manner, but without a catalyst.
  • a first decoupled sensor has a first microheater, a first metallic sensor, and a first catalyst in thermal communication with the first metallic sensor
  • a second decoupled sensor has a second microheater layer, a second metallic sensor layer and a second catalyst layer in thermal communication with the second metallic sensor layer.
  • the controller may be in electrical communication with the first decoupled sensor and the second decoupled sensor.
  • the controller may cause power to be provided to the first and second decoupled sensors to heat the first microheater to a first setpoint temperature and to heat the second microheater to a second setpoint temperature, vary power applied to the first sensor and/or the second sensor to account for a thermal response caused by reactions between an analyte and the first catalyst layer and/or the second catalyst layer to maintain the first setpoint temperature and the second setpoint temperature, and determine an existence, identity, and/or concentration of the analyte based on the varied the power.
  • the first setpoint temperature may be the same temperature as the second setpoint temperature.
  • the detection device includes a reference sensor having a reference microheater and without a catalyst, the reference sensor in electrical communication with the controller.
  • the detection device may include a third decoupled sensor comprising a third microheater, a third metallic sensor and a third catalyst in thermal communication with the third metallic sensor, a fourth decoupled sensor comprising a fourth microheater, a fourth metallic sensor, and a fourth catalyst in thermal communication with the fourth metallic sensor, and a fifth decoupled sensor comprising a fifth microheater, a fifth metallic sensor and a fifth catalyst in thermal communication with the fifth metallic sensor.
  • the first catalyst comprises aluminum copper oxide (AhCuCU)
  • the second catalyst comprises iron oxide (FeiCE)
  • the third catalyst comprises indium-tin oxide (ITO)
  • the fourth catalyst comprises tin oxide (SnO)
  • the fifth catalyst comprises tungsten oxide (WO).
  • the detection device may include a sixth sensor comprising a sixth catalyst selected from copper oxide (CuO) or manganese oxide (MnO).
  • the detection device may include more than six decoupled sensors and each additional decoupled sensor preferably has its their own distinct catalyst.
  • the first catalyst, the second catalyst, the third catalyst, the fourth catalyst, and the fifth catalyst each comprise aluminum copper oxide (AkCuC ), aluminum zinc oxide (AZO), chromium oxide (CrC ), copper oxide (CuO), cobalt oxide (C0O2), iron oxide (FeiCb), indium-tin oxide (ITO), iridium oxide (Ir0 2 ), manganese oxide (MnO), ruthenium oxide (RuC ), tungsten oxide (WO), or tin oxide (SnO).
  • the setpoint temperature may be between 30° C and 500° C.
  • a method of detecting an analyte may include providing a decoupled sensor array comprising a first decoupled sensor and a second decoupled sensor, the first decoupled sensor comprising a first microheater layer, a first sensor layer and a first catalyst layer in thermal communication with the first sensor layer, the second decoupled sensor comprising a second microheater layer, a second sensor layer and a second catalyst layer in thermal communication with the second sensor layer; delivering power to the first and second microheaters to heat the first sensor to a first setpoint temperature and to heat the second sensor to a second setpoint temperature; exposing the first and second sensors to an analyte such that the first catalyst layer and/or the second catalyst layer react with the analyte to generate a thermal response; varying power applied to the first sensor and/or the second sensor to account for the thermal response to maintain the first setpoint temperature and the second setpoint temperature; and/or determining an existence, identity, and
  • Determining the existence, identity, and/or concentration of the analyte based on varying the power may include comparing the thermal response to a database of known thermal responses.
  • the sensor array may include a reference sensor and determining the existence, identity, and/or concentration of the analyte may include analyzing information on power supplied to the reference sensor.
  • the first catalyst layer comprises aluminum copper oxide (AkCuC ), aluminum zinc oxide (AZO), chromium oxide (Cr0 2 ), copper oxide (CuO), cobalt oxide (C0O2), iron oxide (Fe 2 0 3 ), indium-tin oxide (ITO), iridium oxide (hT ), manganese oxide (MnO), ruthenium oxide (RUO2), tungsten oxide (WO), or tin oxide (SnO).
  • AlCuC aluminum copper oxide
  • AZO aluminum zinc oxide
  • Cr0 2 chromium oxide
  • CuO copper oxide
  • cobalt oxide C0O2
  • iron oxide Fe 2 0 3
  • ITO indium-tin oxide
  • hT iridium oxide
  • MnO manganese oxide
  • RUO2 ruthenium oxide
  • WO tungsten oxide
  • SnO tin oxide
  • the second catalyst layer comprises aluminum copper oxide (AI2CUO4), aluminum zinc oxide (AZO), chromium oxide (CrC ), copper oxide (CuO), cobalt oxide (C0O2), iron oxide (Fe 2 0 3 ), indium-tin oxide (ITO), iridium oxide (IrC ), manganese oxide (MnO), ruthenium oxide (RuC ), tungsten oxide (WO), or tin oxide (SnO).
  • AI2CUO4 aluminum zinc oxide
  • CrC chromium oxide
  • CuO copper oxide
  • cobalt oxide C0O2
  • iron oxide Fe 2 0 3
  • ITO indium-tin oxide
  • IrC iridium oxide
  • MnO manganese oxide
  • RuC ruthenium oxide
  • WO tungsten oxide
  • SnO tin oxide
  • the detection device described herein may be used to detect a variety of analytes including but not limited to explosives (including triacetone triperoxide (TATP) and dintrotoluene (DNT)), narcotics and drugs (including fentanyl and cocaine), hallucinogenic and non-hallucinogenic compounds (including cannabidiol (CBD) and tetrahydrocannabinol (THC)), and a variety of other VOCs (acetone, natural gas, propane, etc.).
  • the sensing system is especially designed for a variety of healthcare applications including breathalyzers and wearables.
  • the decoupled thermodynamic sensing system has been used to detect breath, skin, and sweat biomarkers related to a variety of chronic and acute diseases (including diabetes, chronic kidney disease (CKD), Alzheimer’s, and cancer).
  • FIG. 1A shows an illustrative diagrammatic view of the top of a sensor in accordance with an embodiment of the present invention.
  • FIG. IB shows an illustrative diagrammatic view of the sensor in accordance with an embodiment of the present invention, showing the expanded view of the catalyst layer (D), sensing resistor (C), ultrathin substrate (B), and microheater resistor (A).
  • FIG. 1C shows a schematic diagram of an exemplary detection device.
  • FIG. 2 shows a flowchart describing an exemplary fabrication procedure of a decoupled thermodynamic sensor.
  • FIG. 3 shows an illustrative graphical representation which compares the response of a decoupled thermodynamic sensing platform to the previous thermodynamic sensing platform using 20 ppm triacetone triperoxide (TATP) as the analyte at an operating temperature of 175° C.
  • FIG. 4 shows an illustrative graphical representation which displays the response of a decoupled thermodynamic sensing platform to TATP at a variety of concentrations using an operating temperature of 175° C.
  • FIG. 5 shows an illustrative graphical representation which displays the response of a decoupled thermodynamic sensing platform to 20 ppm TATP operating at a variety of temperatures.
  • FIG. 6 shows an illustrative graphical representation which compares of the required power consumption of a decoupled thermodynamic sensing platform to other known thermodynamic sensors operating at a variety of temperatures.
  • FIG. 7 shows an illustrative graphical representation which compares of the response of a decoupled thermodynamic sensing platform employing an indium tin oxide (GGO) catalyst and a SnO catalyst to another known thermodynamic sensing platform.
  • GGO indium tin oxide
  • SnO sulfur dioxide
  • FIG. 8 shows an illustrative graphical representation of the response of a decoupled thermodynamic sensing platform to 5 ppq Royal Demolition eXplosive (RDX) and 0.00002 ppq High Melting Explosive (HMX) at an operating temperature of 175° C.
  • RDX Royal Demolition eXplosive
  • HMX High Melting Explosive
  • FIG. 9 shows an illustrative graphical representation of a comparison between responses of a decoupled thermodynamic sensor employing a AI2CUO4 catalyst to variety of analytes of different vapor pressures at an operating temperature of 250° C.
  • FIG. 10 shows an illustrative graphical representation of a comparison between responses of a decoupled thermodynamic sensor employing an MnO catalyst to variety of analytes of different vapor pressures at an operating temperature of 250° C.
  • FIG. 11 shows an illustrative graphical representation of a comparison between responses of a decoupled thermodynamic ultrathin vapor sensor employing an WO catalyst to variety of analytes of different vapor pressures at an operating temperature of 250° C.
  • FIG. 12A and 12B depict embodiments of sensor arrays in which the substrate is shared by the sensors and in which each sensor has an individual substrate, respectively.
  • FIG. 13 shows a summary table consisting of the thermodynamic sign indicative of the measured redox reactions, for six catalysts making up a decoupled thermodynamic sensor array.
  • FIG. 14 shows a summary table consisting of the thermodynamic sign indicative of the measured redox reactions, for six catalysts making up a decoupled thermodynamic sensor array.
  • FIG. 15 shows an example of a method of using a decoupled sensor array to detect an analyte.
  • Embodiments of the present invention are capable of single molecule detection (of compounds in the gas phase).
  • Embodiments of the decoupled thermodynamic sensors comprise at least two sensors, one or more catalyst coated “active” sensors and an uncoated “reference” sensor.
  • the microheaters preferably are thermally scanned over a selected temperature range and electrically powered, and preferably are configured to maintain a constant temperature. Heat is transferred from the microheater layer (on one face of the substrate) to the sensor layer (on the opposite face of the substrate). After reaching a set temperature and establishing equilibrium, a relatively low amount of electrical power may be provided to the sensor to enable measurement.
  • the power difference between the reference (uncoated) sensor layer and a catalyst-coated sensor layer may be measured.
  • This electrical power difference is the heat effect associated with oxidation/reduction reactions that occur on the surface of the catalyst after decomposition of a target molecule has occurred.
  • Measurement of the power difference between a sensor and the reference may be obtained utilizing a controller integrating Wheatstone bridge circuitry, or more preferably a half- Wheatstone bridge or an Anderson loop for increased efficiency. It will be appreciated that changes in the electrical power of the reference microheater and the catalyst coated microheater may be used to calculate the power difference and thus, the response of the sensor platform.
  • the reference (uncoated) microheater and the catalyst coated microheaters are electrically powered to a predetermined setpoint temperature. Heat is transferred from the microheater (on one face of the substrate) to the thin-film sensor (on the opposite face of the substrate) until equilibrium is established at the setpoint temperature.
  • the vapor sensor system qualitatively or quantitatively measures the heat effect associated with interactions between the catalyst(s) and the analyte.
  • oxidation reactions release heat, resulting in less electrical power required to maintain the same temperature and are therefore associated with negative responses.
  • reduction reactions absorb heat requiring more electrical power to maintain the same temperature and are therefore associated with positive responses.
  • the heat effect may be quantified, as well as qualified as endothermic, exothermic, or neither.
  • Different catalysts used in different sensors in the detection system may experience a different heat effect when exposed to the same analyte.
  • the existence and concentration of an analyte may be determined.
  • the detection system described herein may be used to detect chemical compounds, including explosives (including triacetone triperoxide (TATP) and dintrotoluene (DNT)), narcotics and drugs (including fentanyl and cocaine), hallucinogenic and non-hallucinogenic compounds (including cannabidiol (CBD) and tetrahydrocannabinol (THC)), and a variety of other VOCs (acetone, natural gas, propane, etc.).
  • the sensing system is especially designed for a variety of healthcare applications including breathalyzers and wearables.
  • the decoupled thermodynamic sensing system has been used to detect breath, skin, and sweat biomarkers related to variety of chronic and acute diseases (including diabetes, chronic kidney disease (CKD), Alzheimer’s, and cancer).
  • the present disclosure is an ultrasensitive chemical (vapor) sensing platform, whereby the heating and sensing functions of the sensor platform are decoupled, relative to other thermodynamic sensing platforms, where thin film microheaters serve both purposes or heating and sensing.
  • This decoupling was accomplished by utilizing two different thin-film resistors with one resistor being a heater and the other being a sensor. These resistors were deposited onto opposite faces of an ultrathin yttria-stabilized-zirconia (YSZ) substrate (having a thickness of less than 50 pm).
  • YSZ ultrathin yttria-stabilized-zirconia
  • this sensing platform includes two different thin-film resistors which are deposited in such a way that they are aligned to one another on opposite faces of an ultrathin YSZ substrate.
  • One thin film microheater (resistor) was deposited on the back of the substrate and is electrically powered to maintain a predetermined setpoint temperature.
  • Another thin-film sensor (resistor) is aligned to and deposited onto the opposite face of the substrate and is coated with a metal oxide catalyst. Upon reaching the desired temperature, the thin film sensor (thin film resistor) is “activated” using a small trickle current to measure the voltage.
  • thermodynamic sensing platforms have shown that a reduction in thermal mass yields improved sensitivity and response times at drastically lower operating temperatures.
  • these sensors rely on a single thin film microheater to reach and maintain the desired temperature setpoint as well as detect the target molecules resulting in relatively large operating powers (e.g., greater than 400 mW).
  • FIG. 1A and FIG. IB show a top view of decoupled thermodynamic sensing platform 100 and a cross-sectional view of decoupled thermodynamic sensing platform 100, respectively.
  • detection device 100 may include multiple layers, such as microheater layer 110, substrate layer 120 thin-film sensor layer 130, and catalyst layer 140.
  • Microheater layer 110 may be formed of metal. Microheater layer 110 is designed to maintain a setpoint temperature. In some embodiments, microheater 110 is formed using photolithography to pattern a 1 -micrometer thick film of copper, which has considerably lower thermal mass than free-standing 25-micrometer diameter nickel wires used in other known sensors. Copper is the preferred choice for the metallization due to its high electrical conductivity and thus, low power and voltage requirements. However, any conductive metal can be used including silver and gold.
  • substrate 120 is ultrathin YSZ substrate, which comprises a nominal thickness (e.g., 20 micrometers).
  • Ultrathin YSZ substrates that display a selected temperature difference (e.g., less than 1° C temperature difference) between the front and back of the substrate, due to its thickness anisotropy are preferred.
  • the heat generated from the back microheater remains in the vicinity of catalyst on the opposite face, allowing for uniform heating of the sensor without dissipating throughout the rest of the sensor platform.
  • layers of the decoupled thermodynamic sensor may have different thicknesses, and the films may be optimized for thickness to maximize surface area of the metal oxide catalyst while still maintaining the low mass characteristics of the microheater.
  • Thin-film sensor layer 130 may be formed of metal. Sensor layer 130 is designed to measure power changes via the addition or reduction of heat upon exposure to an endothermic or exothermic chemical reaction, respectively, at catalyst layer 140. In some embodiments, thin- film sensor 130 is formed using photolithography to pattern a 1 -micrometer thick palladium film microheater. Palladium is a preferred choice for the metallization due to its catalytic amplification effect, which has been shown to improve sensitivity and response time.
  • FIG. 1C illustrates a generalized schematic diagram of the internal functional components of an exemplary detection device.
  • Detection device 150 includes a plurality of sensors in communication with programmable controller 155.
  • the plurality of sensors includes first sensor 160, second sensor 165, and so forth up to and including Nth sensor 170.
  • Each of sensors 160, 165, 170 may be constructed in the manner described for the sensor in FIGS. 1A and IB, although in some embodiments, each sensor has a different catalyst.
  • Sensors also may include reference sensor 175, which may be constructed in the manner described for the sensor in FIGS. 1A and IB, although the reference sensor preferably does not include a catalyst.
  • Programmable controller 155 is in electronic communication with each of the plurality of sensors. Specifically, programmable controller 155 may provide a known amount of power to each of the plurality of sensors, though it will be appreciated that in some uses not all of the sensors will be necessary and in such cases programmable controller 155 may selectively provide power to the subset of the sensors that are necessary. Programmable controller 155 is configured to determine the amount of power provided to each of the sensors and to compare the power provided to any individual sensor (e.g., Nth sensor 170) to the power provided to reference sensor 175. Programmable controller 155 may integrate Wheatstone bride circuitry for each sensor, or more preferably a half- Wheatstone bridge or an Anderson loop for increased efficiency.
  • Detection device 150 further includes power supply 180, communication circuitry 185, input/output 190 and user interface 195, each of which are coupled to controller 155.
  • User interface 195 may be used to receive inputs from, and provide outputs to, a user.
  • user interface 195 may provide information to the user on the existence, identity, and/or concentration of an analyte detected by detection device 150.
  • User interface 195 may include a power switch that completes a circuit between power supply 180 and controller 155 to selectively activate an operational mode of device 155.
  • User interface 195 may include a setpoint temperature controller, wherein the user may select one or more operating temperatures for the plurality of sensors.
  • User interface 195 may further include a volume control to selectively increase or decrease an audio output.
  • User interface 195 may include a touchscreen, switches, dials, lights, an LED matrix, other LED indicators, or other input/output devices for receiving inputs from, and providing outputs to, a user.
  • user interface 195 is not present on detection device 150, but is instead provided on a remote computing device communicatively connected to detection device 150 via the communication circuitry 185.
  • User interface also may be a combination of elements on the detection device and a remote computing device.
  • I/O 190 may include ports for data communication such as wired communication with a computer and/or ports for receiving removable memory, e.g., SD card, upon which program instructions or data related to known reactions may be stored and/or for transmitting power to detection device 150.
  • I/O 190 comprises ports, and corresponding circuitry, for accepting cables such that controller 155 is electrically coupled to an externally located computer system.
  • Power supply 180 may supply alternating current or direct current.
  • power supply may include a suitable battery such as a replaceable battery or rechargeable battery and apparatus may include circuitry for charging the rechargeable battery, and a detachable power cord.
  • Power supply 180 may be charged by a charger via an inductive coil within the charger and inductive coil.
  • power supply 180 may be a port to allow device 155 to be plugged into a conventional wall socket, e.g., via a cord with an AC to DC power converter, for powering components within the device.
  • Power supply 180 may be designed to supply power to the components of detection device 150.
  • power supply 180 may, responsive to instructions by controller 155, supply power to each of the sensors to maintain a setpoint temperature/ s) and to vary the power supplied to each of the sensors to maintain the setpoint temperature(s) as the respective catalysts undergo thermal reactions with an analyte (if present).
  • Controller 155 includes electrical components and permits electrical coupling between controller 155 and sensors (e.g., first sensor 160, second sensor 165, N additional sensors 170, reference sensor 175) and other components, when included, such as communication circuitry 185, input/output 190, and user interface 195.
  • Controller includes memory, which may be RAM, ROM, Flash, or other known memory, or some combination thereof. Controller preferably includes storage in which data may be selectively saved. For example, programmable instructions may be stored to execute algorithms for detecting the existence, identity, and/or concentration of an analyte based on the amount of power the controller causes to be supplied to each of the sensors in the array.
  • the instructions may utilize information stored (e.g., in lookup tables) to determine information on the analyte.
  • One or more electrical components and/or circuits may perform some of or all the roles of the various components described herein. Although described separately, it is to be appreciated that electrical components need not be separate structural elements.
  • controller 155 and communication circuitry 185 may be embodied in a single chip.
  • controller 155 is described as having memory, a memory chip(s) may be separately provided.
  • Controller 155 may be a general purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any suitable combination thereof designed to perform the functions described herein.
  • a controller may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.
  • Controller 155 may contain memory and/or be coupled, via one or more buses, to read information from, or write information to, memory.
  • the memory may include processor cache, including a multi-level hierarchical cache in which different levels have different capacities and access speeds.
  • the memory may also include random access memory (RAM), other volatile storage devices, or non-volatile storage devices.
  • RAM random access memory
  • the storage devices can include, for example, hard drives, optical discs, flash memory, and Zip drives.
  • Controller 155 in conjunction with firmware/software stored in the memory may execute an operating system, such as, for example, Windows, Mac OS, Unix or Solaris 5.10. Controller 155 also executes software applications stored in the memory.
  • the software comprises, for example, Unix Kom shell scripts.
  • the software may be programs in any suitable programming language known to those skilled in the art, including, for example, C++, PHP, or Java.
  • Communication circuitry 185 is configured to transmit information, such as signals indicative of the presence, absence, and/or quantity of one or more target analytes, locally and/or to a remote location such as a server.
  • Communication circuitry 185 is configured for wired and/or wireless communication over a network such as the Internet, a telephone network, a Bluetooth network, and/or a WiFi network using techniques known in the art.
  • Communication circuitry 185 may be a communication chip known in the art such as a Bluetooth chip and/or a WiFi chip.
  • Communication circuitry 185 may include a receiver and a transmitter, or a transceiver, for wirelessly receiving data from, and transmitting data to a remote computing device.
  • the remote computing device may be a mobile computing device that provides the system with a user interface; additionally, or alternatively, the remote computing device is a server.
  • communication circuitry 185 may prepare data generated by controller 155 for transmission over a communication network according to one or more network standards and/or demodulates data received over a communication network according to one or more network standards.
  • the decoupled thermodynamic sensing system may be exposed to an analyte such as a chemical compound.
  • catalyst 140 may undergo a chemical reaction with the analyte, which may be an endothermic or exothermic reaction.
  • a chemical reaction with the analyte, which may be an endothermic or exothermic reaction.
  • thin-film sensor 130 experiences any temperature change from the chemical reaction, there may ban an associated demand for increased power to maintain the setpoint temperature in response to an endothermic reaction or a demand for less power to maintain the setpoint temperature in response to an exothermic reaction. This demand occurs at a rate related to the temperature change caused by the chemical reaction with the analyte to which the detection device has been exposed.
  • the power provided to thin-film sensor 130 is minimal due to the effects of the heat transfer provided by microheater layer 110.
  • Exemplary method 200 of forming a decoupled thermodynamic sensor in accordance with the present invention is illustrated in FIG. 2.
  • the heat treatment step 205 involves heat treating a substrate.
  • the substrate is a YSZ substrate, and the heat treatment occurs in ambient air at an elevated temperature (e.g., 1000° C) over a period of time (e.g., three hours).
  • a sensor pattern is applied to the substrate.
  • the pattern is preferably applied using photolithography or shadow masking, but it will be appreciated that other known techniques may be utilized.
  • the pattern includes a serpentine region in which portions of the pattern’s path may remain close to other portions of the pattern’s path.
  • the serpentine region may be sinusoidal, zigzag, irregular, a series of straight or curved segments, or other configuration that may be desired based on heat transfer characteristics, aesthetics, or other desirable characteristics.
  • the sensor layer is applied at step 215.
  • the sensor layer may be applied using sputtering, evaporation, or other known techniques.
  • Step 220 provides an optional decision as to whether it is desirable to remove excess material. If it is not desired, the method proceeds along path 225 to step 240. If it is desirable to remove excess material, such as if photolithography is utilized, then the method proceeds along path 230 to step 235, which involves removal of the extra material.
  • optional step 235 involves lifting off excess palladium metallization, leaving the remaining palladium-based sensor adhered to the YSZ substrate before continuing to step 240.
  • the catalyst layer is applied.
  • a metal oxide catalyst is applied in a layer having a thickness (e.g., 1.2 micrometers) over the serpentine region of the palladium sensor.
  • a microheater pattern is applied to the substrate, preferably in region opposite the face of the substrate on which the sensor is located. Following the application of the microheater pattern, the microheater layer is applied at step 250.
  • the microheater layer may comprise copper that is applied using sputtering, evaporation, or other known techniques, but the microlayer additionally or alternatively may comprise other materials. It will be appreciated that applying the microheater and thin-film sensor to opposite sides of the substrate results in decoupling of the microheater and sensor, which are further separated by the substrate layer. Step 255 provides an optional decision as to whether it is desirable to remove excess material from the microheater layer. If it is not desired, the method proceeds along path 260 to step 275. If it is desirable to remove excess material, such as if photolithography is utilized, then the method proceeds along path 265 to step 270, where the extra material is removed.
  • optional step 270 involves lifting off excess copper metallization, leaving the remaining microheater layer adhered to the YSZ substrate. Annealing is performed at step 275.
  • the copper-based microheater and palladium-based sensor are annealed at a temperature (e.g., 500° C) for a period of time (e.g., 30 minutes) in a nitrogen atmosphere. It will be appreciated that steps for forming the sensor are limited to the order of method 200. For example, in some methods, the microheater may be applied to the substrate before the application of the sensor.
  • thermodynamic sensors in accordance with the present invention, a number of problems were identified and overcome.
  • YSZ substrates displayed increasing electrical conductivity at higher temperatures.
  • This property promoted electrical shorting between a copper-based microheater and a palladium-based sensor.
  • This electrical short was mitigated via precise alignment of the microheater and sensor serpentines.
  • the microheater was able to reach the desire temperature setpoint by transferring any current or voltage to the sensor resistor.
  • the decoupled thermodynamic sensor does not require an aluminum oxide passivation layer between the catalyst and the sensor resistor.
  • the excessive thermal mass associated with the alumina cement caused significant heat loss to the substrate, i.e., significant amounts of heat were dissipated before reaching the catalyst surface, thus producing a temperature gradient between the microheater and the catalyst surface. Removal of this passivation layer not only reduced the thermal mass of the sensor but also more effectively controlled the temperature of the catalytic layer, thereby improving the thermal resolution of the measurement when the catalyst interacted with an analyte.
  • the catalyst layer is preferably 1.2 pm thick metal oxide catalyst layer.
  • FIG. 3 compares response 310 of a previous thermodynamic sensing platform to response 320 of a decoupled thermodynamic sensing platform employing a tin oxide catalyst to 20 parts-per- million (ppm) TATP at an operating temperature of 175° C.
  • the decoupled thermodynamic sensing platform outperformed earlier thermodynamic sensor platforms by several orders of magnitude: i.e., responses of 7000% compared to 20% were realized with the decoupled platform. This represents a 350x improvement in sensitivity relative to earlier thermodynamic sensing platforms.
  • the performance of the decoupled thermodynamic sensing platform can be attributed to two factors.
  • the decoupling of the heating and sensing functions allows for detection of the target molecule at very low operating temperatures with minimal power requirements.
  • the previous platform required approximately 450 mW to maintain an operating temperature of 175°C whereas the decoupled thermodynamic sensing platform only required around 3 mW.
  • the improved performance of the decoupled thermodynamic sensing platform was also attributed to its more efficient thermal characteristics.
  • the microheater that was deposited on the back face of the substrate (exposed to moving air) acts as an insulator, thus, forcing heat transfer in the z-direction (towards the thin film sensor). This unique anisotropic behavior enables unique heating characteristics of the resistors and thus, increased efficiency compared to the previous thermodynamic platforms.
  • the decoupled thermodynamic sensing platform has been used to detect a number of vapor phase analytes (explosives, narcotics, biological analytes, etc.) at trace levels with unprecedented sensitivity.
  • FIG. 4 shows response 410 of the decoupled thermodynamic sensing platform to TATP employing a tin oxide catalyst at 175° C at a variety of concentrations.
  • the sensor showed remarkable sensitivity (approximately 500% improvement over known systems) at the part-per-billion (ppb) level, which represents the dilution limit of the available testing apparatus. Based on these results, detection at the part-per-trillion level and lower is expected.
  • calibration curves for either increasing or decreasing concentrations may be generated for the precise measurement of the concentration of a target molecule (or analyte) concentration in the vapor phase.
  • FIG. 5 shows the response of the decoupled thermodynamic sensing platform to 20 ppm TATP employing a tin oxide catalyst at a variety of operating temperatures. Specifically, response 510 to 75° C, response 520 to 100° C, response 530 to 125° C, response 540 to 150° C, and response 550 to 175° C as shown.
  • the sensor continued to show remarkable sensitivity and selectivity at significantly lower operating temperatures when compared to the inventors’ earlier thermodynamic sensor platform.
  • the decoupled thermodynamic sensing platform showed a transition from exothermic reaction (oxidation) at 75° C to endothermic reaction (reduction) at 100° C and above.
  • thermodynamic sensing platform displayed a sensitivity of -250% to the same oxidation reaction, which represents a 50x increase over previous platforms. Improved sensitivity to these exothermic reactions further improves the selectivity of the overall platform by allowing a single catalyst to be interrogated for multiple reactions.
  • the decoupled thermodynamic sensing platform displays minimal power requirements due to the decoupling of the heating and sensing functionalities.
  • FIG. 6 compares the required operating power of the decoupled thermodynamic sensing platform against previous sensing platforms.
  • the decoupled thermodynamic sensing platform is shown to require significantly less power at all temperatures.
  • power requirement of the decoupled sensor 610 was repeatedly shown to be much less than power requirement of the YSZ sensor 620, power requirement of the nickel- wire sensor 630, and power requirement of the alumina sensor 640.
  • FIG. 7 compares response 710 of another known thermodynamic sensing platform to response 720 of a decoupled thermodynamic sensing platform employing a tin oxide catalyst and response 730 of a decoupled thermodynamic sensing platform employing an indium- tin-oxide catalyst to 20 ppm TATP at 175° C.
  • the indium- tin-oxide based decoupled thermodynamic sensing platform displayed even greater sensitivity: i.e., responses of approximately 115,000% were realized which is a 5750x increase in response over the previous thermodynamic sensor platform.
  • thermodynamic sensing platform 8 shows response 810 of a decoupled thermodynamic sensing platform to RDX and response 820 of the decoupled thermodynamic sensing platform to HMX at these SMD levels.
  • the decoupled thermodynamic sensing platform displayed sensitivities of approximately 100% and approximately 250% to HMX and RDX respectively.
  • Decoupled thermodynamic sensors have also been fabricated employing a variety of other metal oxide catalysts. These include aluminum copper oxide (AhCuCU), aluminum zinc oxide (AZO), chromium oxide (CrCh), copper oxide (CuO), cobalt oxide (C0O2), iron oxide (FeiCE), indium-tin oxide (ITO), iridium oxide (IrCh), manganese oxide (MnO), ruthenium oxide (RuCh), tungsten oxide (WO), and tin oxide (SnO). Each catalyst displays different levels of sensitivity and selectivity based on the chemical reactions that result from the interaction with the target analyte.
  • FIG. 9 shows a comparison of responses of a decoupled thermodynamic sensor employing a AI2CUO4 catalyst to a variety of analytes at an operating temperature of 250° C.
  • FIG. 9 shows response 910 of the decoupled sensor to nonanal (0.48 ppq), response 920 of the decoupled sensor to heptanal (4.6 ppq), response 930 of the decoupled sensor to 2-propanol (59 ppq), response 940 of the decoupled sensor to 2- butanone (119 ppq), and response 950 of the decoupled sensor to isoprene (72 ppq).
  • AI2CUO4 displays highly selective responses to each analyte.
  • AI2CUO4 shows positive (endothermic) responses to nonanal, 2-butanone and isoprene, a negative (exothermic) response to 2-propanol and is completely inert to heptanal. Similar responses are shown for manganese oxide and tungsten oxide (FIGS. 10 and 11 respectively), which are selectivity non-responsive to isoprene while also displaying a response to each of the other analytes. These selective responses represent the foundation for a highly selectivity decoupled thermodynamic sensor array for analyte “fingerprinting.” [0074] FIG. 10 shows a number of responses of a decoupled thermodynamic sensor employing a manganese oxide catalyst to a variety of analytes.
  • FIG. 10 shows response 1010 of the decoupled sensor to nonanal (0.48 ppq), response 1020 of the decoupled sensor to heptanal (4.6 ppq), response 1030 of the decoupled sensor to 2- propanol (59 ppq), response 1040 of the decoupled sensor to 2-butanone (119 ppq), and response 1050 of the decoupled sensor to isoprene (72 ppq).
  • FIG. 11 shows a number of responses of a decoupled thermodynamic sensor employing a tungsten oxide catalyst to a variety of analytes.
  • the specific analytes are nonanal (0.48 ppq), heptanal (4.6 ppq), 2-propanol (59 ppq), 2-butanone (119 ppq), and isoprene (72 ppq).
  • FIG. 11 shows a number of responses of a decoupled thermodynamic sensor employing a tungsten oxide catalyst to a variety of analytes.
  • the specific analytes are nonanal (0.48 ppq), heptanal (4.6 ppq), 2-propanol (59 ppq), 2-butanone (119 ppq), and isoprene (72 ppq).
  • FIG. 1 shows a number of responses of a decoupled thermodynamic sensor employing a tungsten oxide catalyst to a variety of analytes.
  • the specific analytes are nonanal (0
  • FIG. 12A illustrates an embodiment of sensor array 1200 having N sensors and one reference sensor. Specifically, first sensor 1205, second sensor 1210, and other sensors up to and including Nth sensor 1215 are all mounted on substrate 1220. Reference sensor 1225 is also mounted on substrate 1220.
  • decoupled thermodynamic sensors comprise a plurality of microheaters and sensors that do not share a common substrate.
  • a device may include a plurality of microheaters and sensors (including a reference), each with its own substrate to further prevent thermal communication.
  • FIG. 12B illustrates an embodiment of sensor array 1250 having N sensors and one reference sensor. Specifically, first sensor 1255, second sensor 1260, and other sensors up to and including Nth sensor 1265, as well as reference sensor 1270 each are mounted on separate substrates 1275, 1280, 1285, 1290.
  • advantages include increased configuration options, including the ability to position the sensors in different locations relative to one another and facilitated replacement options wherein a subset of a group of sensors may be replaced with other sensors having the same or different catalysts.
  • Sensor arrays display remarkable flexibly and may be placed in a variety of orientations and at any distance with significantly reduced thermal communication between sensors as compared to known systems.
  • the controller of the sensor is used to heat each microheater individually to a pre-determined temperature setpoint. Upon or after reaching the desired setpoint temperature, the thin-film sensor layers are allowed to reach thermal equilibrium with the microheater layers before activation.
  • the catalyst coated sensors and reference sensor are exposed to a target analyte, preferably this exposure occurs approximately simultaneously. The individual redox reactions on the surface of each catalyst results in heat effects which are determined by the controller based on the power usage of the sensors.
  • Each measurement is then compared to (e.g., subtracted from) the reference measurement to help mitigate any false positives or false negatives.
  • An array of separate sensors such as those illustrated in FIG. 12B, could be incorporated into a variety of standalone devices including wearables, breathalyzers, scanning wands, etc. Additionally, the low mass and low power requirements facilitates the use of an array of sensors onboard a variety of mobile platforms including drones, robots, and UAVs.
  • each catalyst Upon interaction with the target analyte, each catalyst has the potential for three distinct responses. As mentioned above, reduction reactions produce positive (+) responses while oxidation reactions produce negative (-) responses. A catalyst may also be unresponsive to a target analyte, indicating the absence of any catalytic decomposition/redox reactions and thus, no response (NR). A “fingerprint” may be constructed for each target analyte based on the response of each catalyst. Thus, a set of pre-determined catalysts can be chosen to allow “selective” identification of each analyte. [0080] The sensor arrays depicted in FIG. 12A and FIG. 12B, like other embodiments disclosed herein, may be configured to be quantitative and qualitative as desired. In another embodiments, sensor arrays can measure the magnitude of each thermodynamic response and provide real-time measurement of the analyte concentration in addition to rapid identification of the analyte.
  • FIG. 13 shows summary table of data 1300 containing the thermodynamic sign (positive or negative), and thus an indication of the measured redox reactions, for six distinct catalysts making up an embodiment of a decoupled thermodynamic sensor array.
  • the table shows that each of the 14 analytes (acetone (10 ppm), ammonium nitrate (AN) (14ppb), RDX (7ppt), H2O2 (7 ppm), TATP (20 ppm), DADP (50 ppm), and 2,4-DNT (180 ppb), CBD (13ppt), THC (0.15ppt), glucose (80ppq), fructose (15ppt), ammonia (7ppm), natural gas (7ppm), and methanol (15ppm)) possess distinct “fingerprints” when the reaction results for each of the six sensors are compared, and these “fingerprints” may be used for rapid identification.
  • a decoupled thermodynamic sensor array formed using some or all of the catalysts in the table could be used to detect an analyte.
  • a decoupled thermodynamic sensor array could also identify which of the 14 analytes was present based on a determination of whether the reaction at individual sensors was endothermic or exothermic and a comparison of the results of the catalysts to the data in the summary table.
  • the data in FIG. 13 may be stored in a database accessible by the controller of a sensor array, and thus, the sensor array may compare heat effects of its sensors to the database of known reactions (known analytes) in order to identify the existence and/or concentration of a particular analyte.
  • Such databases of reactions (with known analytes) using difference catalysts may include the identification of essential and optional catalysts that provide additional flexibility to the sensor array platform by allowing configuration to detect one or more specific analytes, such as a group of analytes associated with explosives.
  • the essential catalysts allow for easy identification of the target analyte while the optional catalysts can be added or removed for redundancy.
  • the data of the summary table could be expanded through further testing with numerous analytes and the addition of other potential catalysts.
  • the data in the database of the summary table is not limited to the catalysts or analytes identified therein.
  • the sensor array can be configured for the detection of explosives, explosive precursors, narcotics, drugs, hallucinogenic and non-hallucinogenic compounds, and a variety of other VOCs.
  • FIG. 13 depicts summary table of data 1300 from a database presented in a tabular form illustrating reaction results of a sensor array having of six catalyst sensors (namely, AhCuC , Fe 2 0 3 , GGO, MnO, SnO, and WO). Sensor arrays including these six catalysts are well-suited for selectively identifying analytes having unique “fingerprints” that are identified as being one of least five explosives, two explosive precursors, one hallucinogenic compound, one non- hallucinogenic compound, and at least five additional compounds.
  • the number of detectable analytes may be selectively increased through further testing and the addition of more sensors having different catalysts.
  • Sensor arrays that include the catalysts identified in FIG. 13 may be deployed onboard a variety of wearables, vehicles (cars, drones, UAVs), and robots to detect explosives in airports, warzones, or any densely populated venues.
  • Sensor arrays including the catalysts identified in FIG. 13 are also well-suited to be deployed by law enforcement in breathalyzers for the detection of THC, as well as by border patrol officers or “TSA Screeners” in a “scanning wand” for the identification of drugs and other illicit materials.
  • Such sensor arrays may be used, for example, as part of a stationary system for the detection of natural gas leaks in homes and industrial settings.
  • sensor arrays may be configured for the detection of biomarkers for a variety of healthcare applications including breathalyzers and wearables.
  • FIG. 14 depicts a summary table of data 1400 from a database presented in tabular form illustrating reactions with known analytes of a sensor array having six catalysts (namely AI2CUO4, Fe 2 0 3 , TGO, MnO, SnO, and WO).
  • Sensor arrays that include sensors having these catalysts are well-suited for selectively identifying and differentiating between acetone, glucose, fructose, ammonia, H2O2, nonanal, heptanal, ethylbenzene, 2-propanol, 2-butanone, and isoprene, thereby providing beneficial diagnostic applications.
  • Acetone and glucose vapors have been correlated to blood glucose at known concentrations.
  • sensor arrays having a configuration of sensors as indicated in FIG. 14 may be deployed as part of a wearable or as a breathalyzer allowing for noninvasive glucose measurement for diabetics.
  • an array of decouple thermodynamic sensors may be deployed as part of a pet collar for continuous, non-invasive monitoring of blood glucose levels for diabetic pets.
  • ammonia is a known biomarker for chronic kidney disease (CKD).
  • sensor arrays having a configuration of sensors as indicated in FIG. 14 may be used as part of a breathalyzer for rapid, real-time diagnosis.
  • H2O2 is present in wounds during the healing process.
  • thermodynamic sensing system may measure H2O2 levels in the wound and provide real-time monitoring of wound healing for first responders. Additionally, nonanal, heptanal, ethylbenzene, 2-propanol, 2-butanone, and isoprene are widely considered breath and skin biomarkers for cancer patients. Thus, sensor arrays having a configuration of sensors as indicated in FIG. 14 may be deployed as part of a wearable or as a breathalyzer allowing for continuous, noninvasive cancer screening and diagnosis. Overall, the decoupled thermodynamic sensing system has been used to detect breath, skin, and sweat biomarkers related to variety of chronic and acute diseases (including diabetes, chronic kidney disease (CKD), Alzheimer’s, and cancer).
  • chronic and acute diseases including diabetes, chronic kidney disease (CKD), Alzheimer’s, and cancer.
  • the tables shown in FIGS. 13 and 14 depict qualitative examples of data from one or more databases of reaction results of various analytes when exposed to sensors having different catalysts. Such data, when used with a sensor array having sensors with pre-selected catalysts, may be used for the selective identification of analytes by the thermodynamic sensor array. It will be appreciated that the data results identified in these tables represents only a sample of the data collected and that additions to the database may be made through further testing with additional analytes and/or sensors having other catalysts.
  • the tables of FIGS. 13 and 14 also represent data that may be used (and expanded on) as part of a database for a sensor platform capable of detecting selected analytes.
  • a sensor array may be special purpose detection devices having sensors with catalysts that are selectively chosen to target one or more analytes falling within a certain category (e.g., explosives, drugs and narcotics, biomarkers, etc.).
  • other embodiments may contain a larger number of sensors and may be capable of serving as a general-purpose detection device, wherein the device may be capable of detecting and differentiating between analytes from a plurality of categories.
  • Exemplary method 1500 of using an embodiment of a sensor array is described in reference to FIG. 15. Method 1500 may be used to determine the existence and/or identity of an analyte and, optionally, the concentration of an analyte.
  • the method begins at step 1510 in which a user has a sensor array with multiple sensors, such as sensor array 1200 or sensor array 1250.
  • the sensor array is activated by providing power to some or all of the decoupled microheaters (including one or more reference sensors) so that the temperature of the microheater of each activated sensor is raised to the desired setpoint temperature.
  • each of the microheaters need not have the same temperature setpoint, and in operation the sensor array may include sensors operating at different temperature setpoints.
  • a plurality of reference sensors may be provided wherein a reference sensor may be provided for each of the different temperature setpoints and used as a reference point for the microheaters having corresponding temperatures.
  • the temperature of the microheater may be adjusted through the delivery of power, wherein the addition of power increases the temperature, while the reduction of power lowers the temperature.
  • the decoupled microheater is allowed to reach thermal equilibrium with the corresponding thin-film sensor.
  • the YSZ substrate possesses highly anisotropic thermal properties such that the decoupled microheater and thin-film sensor should have a temperature difference of less than 1°C.
  • the thermodynamic thin-film sensor for each catalyst and the corresponding reference sensor is then activated.
  • the sensor array is exposed to an environment in which knowledge of the existence, identity, or concentration of an analyte is desired.
  • the sensor array may be attached to a drone and flown in a battlefield, or mounted in a fixed location at an airport, or provided on a mobile platform that may be worn or carried by a user.
  • the analyte reacts with one or more of the sensors in the array.
  • the reaction at each of the sensors is determined.
  • An exothermic reaction at a sensor will produce heat and the corresponding power required to maintain the sensor at the setpoint temperature will be reduced. Fikewise, in response to an endothermic reaction, more power will have to be provided to the sensor to maintain the setpoint temperature.
  • the determination of the reaction at each sensor may be quantitative, in which a determination is made of whether the reaction is endothermic, exothermic, or neither. Additionally, readings of the qualitative magnitude of the power change may be obtained.
  • the reactions at one or more sensors are compared to known results (database for specific analytes and catalysts).
  • the sensor array is in communication with a database of known results (database for specific analytes and catalysts) and a comparison the sensors responses to the known results may be automated.
  • a determination is made as to the existence and/or the identity of an analyte based on the comparison of sensor responses to known reaction results. For example, consider a sensor array for detecting drugs configured with the six catalysts corresponding to FIG. 13.
  • the sensor having the indium-tin-oxide catalyst indicates that an endothermic reaction occurred (requiring the addition of power to maintain the setpoint temperature)
  • a determination may be made that CBD or THC may be present, as each of these produces an endothermic reaction to the sensor with indium-tin-oxide.
  • results from that single sensor may indicate the presence of a drug
  • results from additional sensors are required to identify the analyte.
  • the sensors having the tin oxide and tungsten oxide catalysts each indicate an endothermic reaction
  • the sensors having the AhCuC , FeiCb, and CuO sensors each indicate an exothermic reaction
  • a determination may be made that the identity of the analyte is THC. It will be appreciated that due to the “fingerprints” of the various analytes, an identification may be made of some analytes by using less than six sensors.
  • Some embodiments may include optional step 1560, in which a determination is made of the concentration of the analyte.
  • qualitative data is compared to known results.
  • the change in the power provided to the sensors and the amount of that power may be compared to known results to provide an indication of the concentration of the detected analyte.
  • a rapid change in the power required to operate a sensor may be indicative of a higher concentration of the detected analyte, whereas a more gradual change in the required power is indicative of a lower concentration of the analyte.
  • Graphical results demonstrating the differences in response time and intensity associated with various concentrations of TATP are shown in FIG. 4.
  • thermodynamic sensors employing ultrathin YSZ substrates and Pd-based microheaters display the ability to detect a multitude of compounds in the vapor at the single molecule level both continuously and in real-time.

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Abstract

L'invention concerne des plates-formes de détection thermodynamiques ultrasensibles et découplées pour la détection de composés chimiques en phase vapeur à des niveaux de traces, les capteurs ayant une résistance chauffante découplée d'une résistance de détection. Des modes de réalisation du capteur découplé comprennent une résistance de micro-élément chauffant métallique sur un côté du substrat, et une résistance de capteur couplée à un catalyseur sur l'autre côté du substrat. Un réseau de capteurs peut être fourni, lequel comprend une pluralité de capteurs chacun munis d'un catalyseur différent, qui, lorsqu'ils sont exposés à un analyte, subissent chacun une réaction endothermique, une réaction exothermique ou ne subissent aucune réaction. Une comparaison des résultats de la réaction à des données comprenant des résultats de réaction obtenus précédemment peut être utilisée pour déterminer la présence et l'identité de l'analyte. Avantageusement, les capteurs découplés utilisent moins d'énergie et offrent une plus grande sensibilité que d'autres systèmes connus, et peuvent être utilisés pour détecter et identifier une molécule unique d'un analyte.
EP21899299.8A 2020-11-06 2021-11-04 Système de détection thermodynamique découplé Pending EP4241076A2 (fr)

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WO2022150229A2 (fr) 2022-07-14

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